hydrogen bonding

[Ashley Zhu 1A]

During lecture, Dr. Lavelle said that the partial positive charge on a hydrogen interacts with the/a lone pair on an N, O, or F. I always thought the interaction was with an N, O, or F that had a partial negative charge. Is this incorrect or do both occur at the same time when a hydrogen bond forms? Does the lone pair contribute to the partial negative charge?

[Kassidy Tran 1E]

For a hydrogen bond to form a hydrogen must have a partial positive charge from being bonded to a atom with higher electronegativity (like N, O, or F). The partially positive hydrogen is then attracted to a partially charged negative atom. For example in the case of water, since H is bonded to O which has high electronegativity, the O pulls the electrons towards itself, and is partially negative and H becomes partially positive. Between one water molecule and another, the partially positive H of one molecule can now make a hydrogen bond with the partially negative O of the other molecule.

[Anusha 1H]

You're right about the partial negative charge, which is determined by the electronegativity of the atoms in the molecule.
I think the reason Lavelle made that distinction in class is because a partially negative atom with at least one lone pair has a high density of negative charge, so it is ideal for hydrogen bonding.